西南印度洋洋中脊表层沉积物地球化学特征及其热液活动指示意义

洋中脊热液硫化物勘探技术的滞后，严重制约了对海底热液硫化物资源的勘探开发。以我国西南印度洋硫化物勘探合同区域采集的25个表层沉积物样品为研究对象，基于主量、微量和稀土元素检测数据，采用元素含量特征、相关性分析、元素对比值、特征元素三角图解，以及稀土元素分馏特征值等手段，开展沉积物热液信息研究。结果表明:样品所代表的大部分研究区域内主要为钙质生物沉积，部分样品元素地球化学特征受沉积物中玄武岩风化碎屑的影响，龙旂热液区的部分样品中表现出一定的热液迹象，稀土元素分馏特征和配分模式、（Al+K）?Mg?（Fe+Mn）三角图解可较好地指示热液活动。研究不仅为我国在西南印度洋的硫化物勘探提供基础数据参考，同时也是对海底热液硫化物勘探的沉积物地球化学找矿理论和方法的初步探索。

Elemental Geochemical Characteristics and Significance of Hydrothermal Signature in the Axial Sediments from the Southwest Indian Oceanic Ridge

The exploration of hydrothermal sulfide resources in mid?ocean ridge zones is a critical challenge for the mining sector. In this study, 46 surface sediment samples were collected from the southwestern ultra?slow?spreading Indian Oceanic Ridge area. The sediment types were classified by mineralogical analysis, elemental measurement (including main, trace and rare earth elements) and the material sources of the sediments are discussed. The study showed that biogenic calcareous deposits are a common sediment type in this area; evidence of eolian input was found in some sediment samples with element geochemical characteristics. Signs of hydrothermal activity were observed in some samples near the Longqi hydrothermal areas. The study suggests that characteristics of REE fractionation using an Al+K?Mg?Fe+Mn triangular diagram was an effective indicator of hydrothermal activity. This study not only provides basic data reference for sulfide exploration in the Southwest Indian Ocean, but it is also a preliminary exploration of geochemical prospecting methods for submarine hydrothermal sulfide exploration.